I can understand your frustration, but we have a policy against documenting changing server settings for a hosting provider, because it is important that you utilize their resources for things related to your host. If 1&1 were to change their practices for upgrading versions of PHP, our customers would fail because our instructions were out of date.
For this reason, the error message that PowerStore displays, clearly states "Contact Your Hosting Provider to Upgrade your PHP Server". As nicola stated, she contact 1&1 and got the instructions she needed right away.
This was not an issue with PowerStore "believing" that PHP 5 was installed".
Yes, we have partnered with 1&1 because we know it works with our products. When customers don't know what hosting provider to choose, we recommend one. However, we will not document how to modify server settings for any host, because we cannot guarantee the accuracy of the information. That is up to 1&1.